Scegli dove andare

mercoledì 25 marzo 2015

My "next" regen receiver - Schematic diagram of the RF stages

Here below I copy the schematic diagram of the RF stages of my regen receiver in its current configuration. As said in my latest post on the same subject, the design of the regenerative detector was copied from David Newkirk's web page Receivers for Watching 7120 kHz, with only some minor modifications. From very first tests, it seems that the receiver can work acceptably well from day one, apart from normal tweaking and some stability issues (due to non-ideal mechanical construction). I will post soon a short video clip of the radio in operation.
The actual frequency range (as measured by putting the detector in oscillation and looking for the tone with a Tecsun PL-660 portable in SSB mode) is from about 2400 kHz up to about 7960 kHz.
My reverse computation give about 28 pF to 310 pF for the range of the combined bandset and bandspread variable capacitors; and about 14 uH for the inductance of the tuning coil (I expected 8 uH, based on construction data). I will evaluate later on if it could be worth to try reducing the lower limit of the capacitance (by adding a series fixed capacitor to the bandspread varcap or by using only a single section of it) to extend the upper limit of tuning range, including for example the 31m broadcast band.

Quick update: after having posted the schematic diagram above, actually I made some experiments with the tuning range. I ended up with the decision to use only a single section of both the bandset capacitor and the bandspread capacitor. With this arrangement, the receiver can tune from about 3310 kHz to about 9325 kHz, which is fully satisfactory to me.

Nessun commento:

Posta un commento